[postgis-users] Data storage w.r.t. projections

[Mark Fredrickson]

Hello,

I'm just starting to work with PostGIS, and my first task is to build
a repository of useful geo-political data. To begin with, I'll be
looking at Minnesota, USA exclusively, but I hope to expand to other
states later.

I wonder if anyone has thoughts on which projection I should use to
store my data? All the Minnesota data will be in UTM zone 15, so this
seems like a natural choice. I am wondering, however, if it is more
flexible to store in a projectionless (lat, long) format.

As I understand it, one of the big advantages of UTM is that is allows
for Euclidean geometry, as compared to spatial geometry that would be
required for a lat,long format. Does PostGIS use this feature of UTM
when computing Distance(), etc?

Of course, I could have two geometry columns, one for lat,long, one
for UTM, but this strikes me as unnecessary.

Any thoughts? I've run through the PostGIS manual, but feel free to
point me elsewhere with a "RTFM".

Thanks in advance,
-Mark